Can’t Change Language on Adobe Photoshop?

Techyv, please help!
I am trying to change the language on my Adobe PhotoShop CS5; however, when I try to do this I get an error message. I downloaded a language pack and followed the instructions. Why can’t I change the language? I’m not sure what I’m doing wrong. Does anyone know if there is something special I am supposed to do to change it?

Error message is as follows:
Adobe InDesign CS5 UI Changer Error
An error had occurred while trying to change InDesign's User Interface.
Please ensure that you have installed Adobe InDesign CS5 and you are running this application with administrator's right.
The following shows the error message generated by the system:
System.NullReferenceException: Object reference not set to an instance of an object.
at InDesign_CS5_UI_Changer.FrmMain.ChangeUI(String Success Message, String Error Message)
